1. Field
Apparatuses and methods consistent with exemplary embodiments relate generally to a centrifugal micro-fluidic device for detecting analytes in a liquid specimen and a detection method using the micro-fluidic device and, more particularly, to a centrifugal micro-fluidic device for detection of analytes from a liquid specimen with improved sensitivity. wherein a repeated flow of a liquid specimen induced by both capillary force and centrifugal force enhances reaction efficiency, as well as a method for detection of analytes in a liquid specimen using the micro-fluidic device.
2. Description of the Related Art
In order to cause a fluid to flow or move in a micro-fluidic structure of a micro-fluidic device, a driving pressure is generally required. The driving pressure may be a capillary pressure or pressure generated using an additional pump. In recent years, clinical diagnostic analyzers have been proposed that are designed to enable detection of a target material present in a small amount of fluid in simple and economical ways. One example is a centrifugal micro-fluidic device having a micro-fluidic structure mounted on a circular disc-type rotational platform such as a lab-on-disc and/or a lab compact disc (“CD”).
Lab-on-disc, meaning “laboratory on a disk” is a CD-type device in which various experimental units are integrated for analysis of biomolecules used in a laboratory in order to execute several experimental processes including, for example, isolation, purification, mixing, labeling, assaying and/or washing of a sample on a small disc. Upon introduction of a biological sample, such as blood, into a micro-fluidic structure placed on a disc, the CD-type device may advantageously transfer a fluid such as a biological sample, a chemical reagent, etc. Centrifugal force alone may be used to induce driving pressure and transport the fluid without additional driving systems.
Recently, the use of a ‘lap-on-a-chip’ for blood analysis has been investigated for its ability to rapidly obtain a variety of information from blood samples collected from clinical cases. As a result, a rapid-chip or a rapid-kit has been developed. For such a rapid-chip or rapid-kit, several processes are executed in only a reaction part of the rapid-chip or rapid-kit, including: combination of a material to be analyzed (that is, an analyte) with a detectable signal generator; combination of a composite of the analyte and the detectable signal generator (referred to as “detectable signal generator-analyte complex”) with a capture binder and washing thereof; and the like. However, since the analyte is primarily combined with the labeling reagent, a large amount of labeling reagent is required, although this requirement is seldom satisfied in view of practical aspects. In addition, if the analyte does not fully react with the labeling reagent, an un-combined portion of the analyte and the detectable signal generator may be combined with a capture binder present on a test line, in turn competitively inhibiting the detectable signal generator-analyte complex from being bonded to a control line or test line. Furthermore, combination of the analyte and each reagent is terminated within only a single fluid sample stream in one direction, thus resulting in insufficient combination and causing decrease in sensitivity and difficulties in quantitative analysis. The kit does not have an active device for controlling a re-lysis rate of the detectable signal generator and, therefore, the detectable signal generator is excessively re-lysed by a constant volume of a fluid sample flowing thereto, thus causing waste of the detectable signal generator at an early stage. On the other hand, re-lysis of the detectable signal generator is drastically reduced in a later stage, thus entailing difficulties in sensitive detection of the analyte.